ROME, Sept 8 (Reuters) - Italian bomb disposal experts
safely exploded a device on Saturday left outside the Sardinian
plant of Alcoa Inc., in an escalation of tensions over
the U.S. aluminium producer's plans to shut down the factory.

The controlled explosion of the device, made up of eight
sticks of what initially appeared to be gelignite, was broadcast
on Italian television.

Italian news agency ANSA said it was also equipped with a
fuse that could have allowed it to be set off remotely.

But that was not confirmed by a local police source, who
said the nature of the package was still unclear. "The experts
are still working to establish whether it could have exploded,"
the official told Reuters.

Bomb disposal experts were called after an anonymous caller
told ANSA the device had been left outside the smelter at
Portovesme on the Mediterranean island of Sardinia.

Prime Minister Mario Monti's government is under intense
pressure from labour unions to save the unprofitable smelter at
Portovesme.

It employs some 500 workers with a further 1,000 directly
depending on the plant. Its closure would be a heavy blow for an
island already beset by 15 percent unemployment.

Three workers spent three nights this week camped on top of
a 60-metre (197-foot) water tower at the factory to protest
against its gradual shutdown.

Alcoa said the progressive shutdown, which started on Sept.
1, would continue, but that the smelter would be maintained for
another year "ready to be restarted by another operator, if one
comes forward," according to a statement on Friday.

The firm is scheduled to meet in Rome on Monday with Italian
officials and labour unions to discuss the plant's closure and
any possible offers.